Hi all!
As a side-project of my Kokoan AU I will cover some airlines servicing the archipelago crowded skies.
The AU date for this collection is December 2017, so we are roughly 10 months ahead of this post real date.

The first incarnation of the Kokoan Flag carrier began in 1929 as Koutei Koku Yuso Kabushiki Kaisha (Emperor Air Transport Corporation). Named after the Emperor Archipelago on which Koko sat, the State-owned arline started domestic services with 5 Fokker Trimotors, later augmented by Nakajima Ki-6, Douglas DC-2, Nakajima Ki-34 and Lockheed-14 aircrafts. Despite a promising start -a few international routes were added since 1933-, scheduled civilian service ended in early 1942 soon after the start of the Pacific War, with military flights being operated on behalf of Imperial Japanese Airways until Koko uprisings put an end to them in early November 1945.
although never officially disbanded Koutei Koku had effectively ceased to exist by that time.

After the war, until early 1949, all civilian (other than military) aviaton in Koko was effectively banned under peace treaty clauses, with domestic and international services provided by PanAm, Northwest Orient and Hawaiian Airlines. Kokoan airspace was finally reopened to domestic operators by mid 1949. One of the companies that were founded by the end of the year was the state-owned Retto Kido (Archipelago Airways), which immediately became Koko's de-facto Flag carrier and successor of the pre-war Koutei Koku. Scheduled passenger service started in late 1949 with two second-hand Douglas DC-3 previously operated by PanAm. As the DC-3 fleet was augmented with the addition of extra airframes the douglas DC-4 joined the fleet in 1951, followed in 1954 by the DeHavilland-114 Heron which operated on northern routes that required sturdier aircrafts for rougher runways. At the time, the airline operated 24 aircrafts, all left bare-metal with the exception of the company logo -a silhouetted seagull inscribed in a circle- just aft of the cockpit windows and the airline name written both in western style and in Hiragana over the side windows.
Things changed in 1955 with the delivery of the Douglas DC-6, which started the first international service operated by a Kokoan airline in 14 years. Retto Kido was rebranded as Koutei Koku (Emperor Airlines), thus regaining it's old name and all aircraft recieved red and blue cheatlines on the fuselage and a white top, the red and blue pattern was replicated on the lower half of the vertical stabilizers, with the top half beign red. The seagull logo remained near the cockpit bt was also replicated on the tail, and the dual Koutei Koku/Emperor Airlines - the latter much more prominent- was painted above the fuselage cheatlines. Further expansion came in 1959 with the introduction of the Douglas DC-7 and Convair-440. The first operated international service to San Francisco and Los Angeles (via-Honolulu), the latter augmented the Herons and DC-3s on domestic routes.
Koutei Koku entered the jet age in 1960 with the delivery of the Douglas DC-8-10, used on domestic routes between Toumachi, Kumoi, Hoshiguma and Taniguchi. DC-8-30 and C-8-50 for international services followed in 1961 and 1963 respectively, opening new routes to the US, Australia, Japan, South Korea, Taiwan and Hong-kong. 1961 also saw the introduction of the Fokker-27 on regional routes, wich largely replaced the DC-3s, the Herons and even the DC-4s, wich by that time had been relegated to domestic service.
The year 1964 saw the delivery of the first Boeing 727-100, an event which had it's own degree of significance. Up to that time Retto/Koutei had been a loyal Douglas customer, owning all major aircraft produced by the American manufacturer from the DC-2 to the DC-8, now for the first time, it had chosen Boeing's 727 over the DC-9. The first sign of a shift that will materialize later. In 1966, to retire the last, antiquated and worn out DC-3s, the Japanese-manufactured NAMC YS-11 turboprop was introduced. The DC-8-62 followed in 1968 to further expand international routes.
In 1968, twenty years after having restarted operation, Koutei Koku had a fleet of 109 aircrafts and a higly developed internal and international network, with scheduled flights to Hawaii, the US west coast, Canada, Japan, South Korea, Taiwan, Philippines, Indonesia, Australia, New Zeealand, Chile, Argentina and the first route to Europe (London), via-Anchorage and New York. However this vast expansion came with a cost. In it's early years the arline was literaly marred by accidents: eight planes where written off in accidents between 1952 and 1967, six of them resulting in passenger casualties. This culminated in 1968, when a 727 departing from Toumachi Airport failed to properly get airborne -the investigation revealed the crew had improperly set the plane for takeoff-, clipped the airport perimeter fence and slammed into the nearby residential neighborhood, killing all 114 on board and 44 on the ground. Resulting in what was the deadliest aircraft accident at the time.
As a consequence training methods and crew schedules were heavily revised in an effort to improve the arline safety record, All prop and turboprop aircrafts -with the exception of the NAMC YS-11- were retired in the next few years: if 61 out of 109 planes were propeller-driven in 1968, that number was down to 28 out of 111 in 1974. Then, in an unprecedent move, Koutei Koku was privatised in early 1970. The livery was changed as well, with a simplified red and blue cheatline and a white tail with an enlarged blue seagull logo. The smaller seagull disappeared from the fuselage, as well as the kanji-written Koutei Koku, leaving only the western styled Emperor Airlines denomination.
In 1969 the arline had added the Boeing 727-200 and 737-200 to its inventory, preferring once again a Boeing product over the improved versions of the Douglas DC-9.

Koutei Koku then entered the age of mass-transport in late 1970 when the first widebody, a Boeing 747-100 joined the fleet. The huge aircrafts operated on high-density domestic routes, replacing most of the DC-8-10 and 727-100, wich were withdrawn from service during the same timeframe. In 1971 the airline also recieved the Boeing 747-200 to boost international routes (all DC-8-30 and some DC-8-50 were retired as a consequence). As the last act of this large fleet renewal, Koutei Koku ordered the McDonnell-Douglas DC-10-30 for all international routes that had no need of the 747 capacity. While the 747s were common sights in all southeast-Asia and west-coast US airports serviced by Koutei, the DC-10s flew to all other destinations to the US, South America, Recerche and Australia, the exception beign NY and London. The trijets were the last aircrafts purchased by the Kokoan airline from the MDD manufacturer.
After growing from 2 to 110 aircrafts in 20 years Koutei's fleet remained somewhat stable, bouncing between 106 and 118 machines until the mid 80's, mainly as the result of the introduction of the large-capacity widebody aircrafts. The 70's oil crisis di affec the airlines, but thanks to Kokoan sizable own oil production Koutei suffered much less than many other carriers and quickly returned profitable without significant cuts. The 70's decade also saw the last two Koutei Kokou accidents that resulted in passenger fatalities: in 1973 a DC-8-50 crashed short of the runway while trying to land at Osaka Airport in bad weather, resulting in 52 fatalities (out of 126 on board). In 1977 a NAMC YS-11 suffered an engine failure during a flight between Hokuto and Mizushimo, one of the propellers disintegrated and a blade cut into the fuselage, killing 2.
As the airline finances improved, more boeing 747 were ordered. The BSR versions of the 747-100 specifically designed for domestic use, and more 747-200 for international service (replacing all DC-8-50 still in service). Another batch of 747-200, this time of the Freighter version, were ordered in 1979 for the newly enstablished Koutei Cargo division.
In 1980 the airline recieved its first twin-engined widebody when the first Airbus A300 was delivered late the same year. It was the first time Koutei Koku had ordered a non-US manufactured plane in 14 years, and the first overall for a jet-airliner. The A300 was perfectly suited to operate on thinner domestic routes and a much more economic plane to operate than a DC-10-10, which the airline was considering for order before choosing the go for the twinengined alternative. The satisfacion of the arline wth the Euroepan-built plane would later led Koutei Koku to order the A300-600 as soon as it made the first flight in 1983. This obviously did not meant that the airline was not happy with its 747s, as the 747-300 joined the fleet between 1983 and 1991. Mosto of them were of the long range version while a few of the -SR version augmented domestic service. The 747-300 replaced the last DC-8-62 that were still in service. Another old aicraft, the 727-200 was withdrawn from service in the late 80's replaced by 737-300, delivered between 1988 and 1991. The A300-600 previously ordered started to join the fleet in 1987.
During the second half of the 80's Koutei Koku moved its headquarters to the newly built Ryujin International Airport. Ryujin replaced the now congested Toumachi Airport, which was completely surrounded by urbanizaiton and lacked available land for much needed expansion. Ryujin International, which handled 84milion passengers in 2016, is still Koutei Koku main Hub, as well as a Focus City for PanAm, which is the only carrier other than Koutei to boast 68 years of continous scheduled service at either Toumachi or Ryujin airport. The now unrestricted operations in the new airport allowed Koutei koku too boom and increase by 60% it's international network, beginning widespread service to Europe and South America, adding Thiaria as well.
The early nineties saw the introduction of the Boeing 747-400 and it's domestic, high-capacity, sibling, the 747-400-D in 1990 and 1992 respectively. The Airbus A320 joined the narrowbody fleet in 1991, and Its larger sibling, the A321 joined the fleet in 1995, followed by the Boeing 777-200. The year 1995 also saw the first livery change since 1970, with the cheatline gone, replaced by the entire top-half of the airplanes painted blue, tail included. The seaugull on the vertical stablizer -now white- was made taller, while the fuselage showed again -the first time since 1969- the dual Emperor Airlines / Koutei Koku name, the latter written in kanji.
1995 also saw what was, to date, the last fatal accident involving a Koutei Koku airplane: a 747-200 Freighter bound for Anchorage was caught by severe weather shortly after takeoff, leading to the surge of n°4 engine. The aircraft attempted to return to Ryujin International Airport but encountered violent turbulence over Mount Yashima which caused the crew to lose control of the plane, which eventually broke up in flight.

As the decade progressed, the venerable NAMC YS-11 that still operated on regional routes on the northern islands started to be replaced by Bombardier DHC-8-300 and DCH-8-400. The Airbus A330-300 joined the fleet in 1996, followed by the Boeing 777-300, both types operating on domestic routes. More 747-400 joined the international fleet in the late 90's. By that point, Koutei Koku's growth, which had led to a fleet of over 200 aircrafts by 1996 hit a lull caused by the Asian econimic crisis of 1996/1997 first and the decrease of air traffic following 9/11. This prompted another large fleet renewal: some 747-300 were sold to Pan Am after a few routes to southeast Asia became unprofitable. The older A300s were retired by 2005, the 737-200 in 2002, the 747-100 and the 747-sr in 1999 and 2005 respectively. The DC-10-30s were withdrawn from service by 2005, the passenger 747-200s followed in 2008, the 747-300-sr and all 747-200 freighters in 2009. Older 747-400s were also retired in 2008-2009 and converted into freighters.
During the same timeframe, newer and more fuel-efficent planes were added instead. In 2000 the first 777-200-er was delivered, the 777-300-er joined in 2004. Airbus A330-200 for long-haul routes were delivered in 2002-2006, followed by A330-300 for domestic service in 2006-2014. The Airbus A319 saw it's introduction in 2004. The Boeing 747-400 freighter joined as a replacement of the 747-200. To expand medium-range thin routes too small for the A330, 777 or 747 capacity, Koutei Koku also ordered an entire fleet of Boeing 737-800, recieving them between 2007 and 2016.
The year 2008 saw the fourth livery change in Koutei Koku history. The blue on the fuselage was moved from the top half to the lower half, this time with a red cheatline going from the front of the vertical stabilizer to the nose of the plane. The seagull on the tail was made smaller, as a shilouhetted Mount Yashima was added below it. Finally, the dual name on the fuselage disappeared, leaving only a large billboard style Koutei written in western alphabet. A variant of this livery introduced in 2012 on newer cargo planes removed the blue underbelly, leaving only the tail and aft section not beign painted white.
A second wave of fleet renewal saw the retirement of the 747-300 in 2011, the A300-600, Boeing 737-300 and 747-400-D in 2013. In late 2011 the first Boeing 787-8 joined the fleet, the dreamliner replaced the A300-600 and was later augmented in 2014 by the 787-9, which Koutei Koku has ordered to replace the 777-200 and expand the international fleet as well. The cargo fleet was augmented by the delivery of the Boeing 747-8-F between 2012 and 2015, which offset the simultaneous retirement of the 747-400-BCF. The airline also recieved in 2013 the Airbus A-330-200-F, which proved succesful enough to warrant an order for further airfames, the firt of them delivered from 2017. Last addition to the international fleet has been the Boeing 747-8-Intercontinental. Having recieved the freighter a year before, Koutei Koku choose the last developement of the 747 over the A380 as its long-haul flagship.
For decades Koutei Koku has not owned a dedicated regional division but kept the turpoprops doing the job in it's mainline fleet. This changed in 2015 when, facing greater competition by low-cost carriers and other regional airlines, Koutei Koku announced the acqusition of Kita no Kokukaisha (Northern Airlines), a sizable but economically troubled regional airlines based in Miyabi. The acquisition led Kita to be rebranded as Koutei Connection in 2017, repainting it's aircrafts in Koutei colors. All DHC-8-400 in Koutei mainline fleet are currently being transferred to Kita to replace its older planes. To replace DHC-8 Koko's Flag carrier stuck a deal with Thiarian SCI for their Toscaire-300 -surprising most aviation enthusiast who thought Koutei Koku would have placed an order for the Bombardier CS-100 or the Embraer E-190-E2-, whose delivieries started in the second quarter of 2017. As for the mainline fleet, the A320Neo started beign delivered in October 2017 as part of a large order -over 70 machines- to renew the entire short-haul narrowbody fleet.
Koutei koku has currently on order 10 A330-900Neo (to replace the 6 oldest A330-300 in the fleet) 2 A330-200F, plus 8 A319Neo, 21 A320Neo and 45 A321Neo, for a total of 86 machines on order with the Airbus consortium. It is also rumored that during the 2018 Singapore Airshow Koutei Koku might finalize a large order for the A321LR to replace all it's remaing 737 fleet.
Boeing got it's own share as well, with 30 Boeing 787-9 and 10 787-10 (3 ordered in 2015, 7 more January 2017), 3 747-8-i, 4 777-300-er, 5 777-8 (announced in June 2017) and 29 777-9. for a total of 81 planes.
The 787-10 will replace the 777-300s on domestic market, while the 777-X orders will cover and augment the planned retirement of the 747-400, most of which are to leave service by 2020. In addition to the official 747-8-intercontinentals backlog, Koutei Koku has signed a deal with Boeing take over the four unsold airframes intended for the bankrupt Transaero.

Currently, Koutei Koku operates a fleet of 293 mainline aircrafts, 18 freighters ( plus 37 turboprops under the subsidiary Koutei Connection). Depending on the interpretation, it is either the largest airline in Oceania or the fourth-largest in Asia (and the largest outside China). Koutei planes fly to 65 domestic and 114 international destinations in 55 countries. Plus 5 domestic and 20 international cargo routes in 14 countries.

Retto Kido began its first operations with two former Pan-Am Douglas DC-3s (which were in turn former USAF C-47s) on August 13th 1949. more airframes were added in 1950 and during the following years, as Retto would ultimately own 14 of them by 1954, 13 beign in service at the same time. Actually a mix of C-47s and C-47A, the Douglas twin-engined monoplanes were the backbone of the fleet operating all early short-haul connections operated by the arline. Sturdy and well regarded they were however often in the spotlight for the wrong reasons: five were written off in accidents, in 1952, 1959, 1961 and twice in 1963. Four times this resulted in passenger fatalities.
The rebranded Koutei Koku eventually started retiring the venerable planes after the twin crashes of 1963. Replaced by Fokkers-27 and Namc YS-11 the last three DC-3 left the fleet in late 1966.

A special thank to Eswube for providing me the updated blank for the DC-3

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Ten of this four engined plane joined the fleet between 1951 and 1955, all second-hand airframes that were previously in service with US arirlines. Despite beign used as trascontinental or long-range aircraft by most airlines, Retto Kido operated the DC-4 on domestic routes along the DC-3, usually filling higher capacity trunks (like Toumachi-Hoshiguma) or routes that involved long stretches over water (Miybi-Miyamori beign the most blatant example) where four-props granted more redundancy in case of engine failure. Unlike the Dakotas, Koutei's DC-4 were exempt from any mishaps, none were involved in incidentes, the only notable event happened in 1962 when one of was bumped by a Pan-Am 707 during taxi operations.
Four were retired in 1959-1961 when the Convair-440 entered service, the other six kept serving for a few more years before beign all withdrawn in late 1963.

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This small four-engined propeller driven aircraft was introduced in 1954 to serve Retto Kido's northern routes. As with the except for Hokunada and Mizushimo most airfileds in Shinjima, Kitajima and Gensho had gravel and unpaved runways, for which the Heron was well suited. Six were in service by 1957, and they were remarkable in their own way as they were the first factory-built planes the airline purchased. The first three were delivered with Retto Kido unpainted fuselage, while the other three got the new livery of the rebranded Koutei Koku from the start. In service they proved reliable and none was involved in trouble despite the rugged environment in which they operated. They were short-lived however. Replaced by Fokker-27s all were retired by late 1964, averaging less than 9 years of service each.

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The first true post-war Kokoan international service began in 1955 with the delivery of the fisrt Douglas DC-6B, the same year Retto Kido rebranded itself as Koutei Koku adopting a new painscheme which debuted on this aircraft. Deliveries from Douglas lasted until early 1958, when eight such planes had been put into service for scheduled flights to Guam, Tokyo, Honolulu and Anchorage. During their service time there was just a single serious occurence, when one damaged beyond repair in 1961 following an hard landing at Honolulu, luckily without casualties. Two left service in 1963 when the first DC-8-50s entered service. The last five airframes were progressively removed from long-range routes and shifted to domestic service before beign ultimately retired in 1967-68.

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Twelve second-hand CV-440s entered service in 1959-1962 augmenting the Herons, DC-3 and DC-4 on domestic routes, partly replacing the latter. One of the aircrafts was part of one of the darkest pages of Koutei Koku's history when, on February 17th 1966, it exploded in misterious circumstances during a routine flight between Chiyoko and Kumoi, killing all 43 on board. The culprit and its motivations were never identified. To date, this remains the only bombing in Kokoan aviation history. Another airframe was written off the same year when it skidded off the runway during landing at Minazuki Airport but there were no casualties. The other 440s enjoied a much quieter career and remained in service until 1970 when they were replaced by Namc YS-11.

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Delivered in December 1958, starting scheduled service during the first months of 1959, the four DC-7C recieved by Koutei Koku held the particular distinction of being the last ever of their type to be produced by Douglas. Augmenting the DC-6Bs they became the airline long-haul flagships (until the first DC-8-30s were delivered in 1961) and served the transpacific routes to San Francisco and Los Angeles (via-Honolulu). They had quite luxurious interiors, if compared to the other planes in the fleet, fitted to seat 70 passengers. One was lost in 1967 after suffering an engine failure shortly after taking off from Honolulu. All but four of the 65 on board survived the forced ditching. The other three were retired in 1970.

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Sources and documentations are the most welcome.